Modern communication systems utilize various modulation techniques to transfer information. Some examples of common modulation techniques include frequency modulation (FM), amplitude modulation (AM), phase modulation (PM), and the like. Frequency modulation is a form of modulation that conveys information over a carrier wave by varying its instantaneous frequency. Phase modulation is a form of modulation that represents information as variations of an instantaneous phase of a carrier wave.
One factor for the various modulation techniques, including phase modulation, is the range of frequencies used. The range of frequencies is typically referred to as bandwidth. One variation is narrowband bandwidth, typically used for some radio transmission systems. Narrowband uses a relatively narrow range of frequencies. Another variation is wideband bandwidth, typically used for FM broadcasting of music and speech. Wideband uses a relatively wider range of frequencies, but can have lower signal to noise ratios.